Maximum fording capability

[biggoolies]

Hi. I am preparing my truck for a six month journey to Mexico. I don’t think I will have time to raise the current height of the breathers before going and will have to wait until next year to do that job. I require the maximum fording capability I can do for the trip. My truck is a stock 2006 FG. No change to the suspension or rims/tires yet. Thanks. I don’t want to do any damage to my beloved drivetrain.

 

[gait]

my FG649 has breather pipes to a higher point within the chassis rails on both diffs. Not sure about transfer case and gearbox. The low point is the bottom of the air filter. There's a "one way valve" in the bottom of the filter case and another in the exit (engine side) box. I've replaced the rubber bits and keep the seats clean but I don't really trust them and consider the bottom of the filter to be the maximum depth I will normally cross. I ford creeks and rivers in 4wd, max 2nd gear, usually slower.

Having said that I have forded deeper when trying to escape flooding. I minimise the time at that depth. The filter is behind the dust flap for the wheel which tends to keep the bottom of the filter reasonably clear of water.

 

[kerry]

I’ve wondered myself how reliable those little rubber flaps are.

 

[Amesz00]

You should be fine up a metre. I've had a 649 with stock intake setup that saw around 4ft a few times, never got water in anything. It did have bigger tyres and suspension though.
My current 84 (140) has also seen over a meter a few times with no issues. Only time I got water ingres was when I crossed a 1.5m river. Got a little water in the fuel and the front diff. Would not recommend that lol.

 

[Spanna 53]

For as long as it takes , a couple of meters of 6 mm fuel hose , hose clamps ,cable ties , and a couple of 1/4" in line fuel filters high as in the chassis rails , my front diff transfer case and gear box breathers are on the front of the camper just to get them up higher still ,crossed several rivers and fords (see Steves video of Ivenhoe crossing ) and you don't get the pressure build up then cooling down that causes the water to suck in the gear box /diff its most noticeable when checking the fluid levels a little time well spent I felt .

 

[canter tourer]

Anytime someone asks about how deep you can go, this always springs to mind. A sure fire way to stuff a truck!

Dave.

 

[SkiFreak]

Just remember... if you are going through water that deep, make sure your windscreen wipers are on.
Well, that's how the "professionals" do it.

 

[biggoolies]

You should be fine up a metre. I've had a 649 with stock intake setup that saw around 4ft a few times, never got water in anything. It did have bigger tyres and suspension though.
My current 84 (140) has also seen over a meter a few times with no issues. Only time I got water ingres was when I crossed a 1.5m river. Got a little water in the fuel and the front diff. Would not recommend that lol.

Wow. 1.5 metres. That must have been fun. ??

 

[Buddha.]

Anytime someone asks about how deep you can go, this always springs to mind. A sure fire way to stuff a truck!

Dave.

 

[yabanja]

Somewhere way back on this forum is a long article from some of the guys who ran tours on the beach down under. They said the most important thing is to stop and let the axles cool before entering water or the heat will draw water in through the wheel seals. I have driven through 4 feet of water with no water intrusion after inspecting all fluids. I have all stock breathers.

Allan

 

[biggoolies]

With allowing the differentials to cool, was it said how long in time to allow it to cool before proceeding?

 

[SkiFreak]

The bottom line is that the majority of seals in the diffs, gearbox and transfer case are lip seals, which are primarily designed to stop oil getting out.
When the diff is hot, so is the air inside it. If you rapidly cool the diff, by immersing it in water, you will also cool the air inside, which will create a low pressure zone if the breathers cannot equalise the pressure quickly.
To that end, you need to make sure that the breathers have as little restriction as possible. Obviously, if the end of the breather pipe/s is below the water the low pressure in the diff will suck water in through them, hence the reason why it is recommended that you raise the breather height if you plan on crossing deep water. If the breather pipe is blocked, that low pressure will suck water past the oil seals, no matter how high the breathers are.

So, to answer your question...
If your diffs/gearbox/transfer case breathers work well, it is less likely that you will get water where it should not be.
As I eluded to, if the breathers are working as designed, quenching a hot diff in water should not create a low enough pressure inside to suck water past the seals, but it is normally prudent to let the diff cool down a bit, just to be safe.
Use common sense to determine when it is okay to immerse them in water.

 

[whatcharterboat]

Somewhere way back on this forum is a long article from some of the guys who ran tours on the beach down under. They said the most important thing is to stop and let the axles cool before entering water or the heat will draw water in through the wheel seals.

That was Engineer speaking from experiences mainly on Cape York which is often worse than the beach... Cause you'll be driving for long period in high temps then come to a deep creek crossing and the hot diffs will suck water in. When we drive buses on the beach the diffs don't get as hot although I must say the creeks can get pretty deep on the top of a 2.6metre tide.

 

[Tudor Tanase]

East European military trucks often had pressurised drivetrains, which is something I'm surprised no one is offering these days. It's just a manually activated system pushing air at 2-3psi or so into the housings via the breather lines to create a positive pressure inside diffs etc which as good as guarantees no water ingress. Just switch on before crossing and off once out of the water.

 

[DzlToy]

Since many of these trucks have an OBA system of some kind, a very small tank could be left pressurised at 2-3 psi, with all of the "breathers" being fed into that tank. Unless there is a reason they can't take 2-3 psi continually, just leave it on and increase the chances of keeping water, mud or debris out of your diffs and transfer case.